1. Field of the Invention
This invention relates to the generation system of design data, a generation method of design data, a recording medium and a program.
2. Description of the Related Art
Eyeglasses using inner surface progressive addition lenses as a far-and-near glass lens have been used in recent years when accommodation power of eyes drops due to presbyopia or the like. This inner surface progressive addition lens is a lens having different power. For example, an upper portion of the lens is a distance portion for seeing distances, a lower portion is a near portion for seeing near distances and a portion between the distance portion and the near distance portion is a progressive portion in which power progressively changes. Curvatures constituting the distance portion, the near portion and the progressive portion are imparted to an inner surface (progressive surface) positioned on the eyeball side as described, for example, on pages 2–5 of JPA-A-2002-122825, the entire disclosure of which is incorporated herein by reference.
A generation method of design data of such an inner surface progressive addition lens uses, for example, a three-dimensional function expressing a cubic surface such as a high order polynomial. A method that forms a power area for a distance portion (distance portion), a power area for a progressive portion (progressive portion) and a power area for a near portion (near portion) in the function and creates a necessary progressive surface by parameters is available as described in JP-A-2002-122825.
The shape of the progressive surface of the inner surface progressive addition lens varies depending on prescription data of the lens (such as spherical power, cylindrical power, cylinder axis, addition power, etc) and individual lenses must be designed in accordance with the prescription data. The design method described above acquires the prescription data, calculates the distribution of power and the curvature on the basis of the prescription data and calculates the function. However, there remains the problem that generation of the design data is time consuming.